Mary Ainsworth studied and showed that attachment helps to lessen anxiety.
It allows a child to leave the attached figure and explore the surroundings. A transitional object, which is an inanimate object, such as a teddy bear or a blanket, also works as a secure-base. Children carry it along as they examine the environment.
Sadock, B. J., & Sadock, V. A. (2015). Kaplan & Sadock Synopsis of Psychiatry: Behavioral Sciences/Clinical Psychiatry. Wolters Kluwer, Philadelphia, Pa. https://doi.org/10.1097/00004850-198907000-00008
Duschinsky R. The emergence of the disorganized/disoriented (D) attachment classification, 1979-1982. Hist Psychol. 2015;18(1):32–46. doi:10.1037/a0038524